Cork composition and method of making same



Patented Sept. 10, 1935 STTS CORK COMPOSITION AND METHOD OF MAKING SAME Herbert Paschke and Clarence C. Vogt, Lancaster, Pa., assignors to Armstrong Cork Company,

' Lancaster, Pa., a corporation of Pennsylvania No Drawing. Application October 9, 1931, Serial No. 567,976

8 Claims.

Our invention relates to a cork composition, particularly to a cork composition formed from reclaimed, reground scrap cork composition.

It is an object of our invention to produce a 5" cork composition that may be formed from the scrap of previously formed cork composition. It is a further object of our invention to provide such a cork composition that will compare favorably with compositions formed of raw cork. It is 10 a further object of our invention to provide a method whereby scrap from cork composition can be utilized in the manufacture of a second cork composition. Other objects of our invention will become apparent to those skilled in the art to 1'5 which it appertains upon reading the following specification.

Ordinary cork composition is formed by grinding particles of cork to a desired substantially uniform size. These cork granules are treated with a binder and are charged into a mold. The mold is subjected to pressure and heat at about 220 to 240 F. for a period of from four to twelve hours. Cork is a good insulating material and, for this reason, it takes a comparatively long v baking period to set the binder completely throughout a block or mat of cork. The binder generally used is composed of a mixture of glue or other protein, a softening agent such as glycerine, and a tanning agent such as formaldehyde.

When a binder consisting essentially of glue treated with formaldehyde is used to make the cork composition it forms a formaldehyde-gelatine complex. The action of the formaldehyde on the glue and gel-atine is similar to the tanning action of formaldehyde on hides. This reaction, as has been shown in the tanning industry, is reversible and can be made to reverse by heating in the presence of water. That is, if the formaldehydegelatine which is formed by heating the binder in the first instance is treated with water under heat and pressure, it will revert to glue and formaldehyde.

The degree of reversion of the formaldehydegelatine depends upon the temperature, pressure and quantity of water to which it is subjected. If the quantity of water, the temperature and the pressure are sufiiciently great, the formaldehyde-gelatine will be completely changed to glue and formaldehyde. The formaldehyde which is formed by the reversion of the formaldehydegelatine readily volatilizes in the presence of steam and may in addition undergo oxidation or other chemical changes.

When proteins other than glue are treated with formaldehyde .or other tanning agents insoluble complexes similar to formaldehyde-gelatine are formed. These complexes are also affected more or less by treatment with water under heat and pressure. Ihis results in the partial disintegration of the binder. 5

Accordingly, it may readily be seen that it is not possible to make a good cork composition out of reground cork composition in which any appreciable quantity of the original binder is presout. This has been tried many times but has 10 always resulted in failure because the original binder hydrolyzes under the continued heat and pressure in forming a new composition and the bond is materially deteriorated. This results in the separation of some of the cork granules from 15 the composition.

No one has, up to the present time, devised any method whereby the original binder of the cork composition can be removed in a commercially practical manner. original cork composition is reground, the binder at many points is stronger than the origin-a1 cork granules. That is, the adhesion between adjacent cork granules due to the presence of the original binder is greater than the cohesion within the 25 individual cork granules. Accordingly, the granules formed by grinding the scrap from the original cork composition may be composed of portions of a plurality of different granules of the original cork composition. In other words, one 30 granule of the reclaimed cork may consist of several small portions of cork, each of which formed a part of a separate cork granule in the original cork composition. These small portions are still bound together by the binder which bound 35 the different granules together in the original cork composition.

By means of our invention we may utilize these granules of reclaimed cork, which have been reground from scrap of previously formed cork com- 40 position, without the necessity of performing any expensive operation upon the original binder. The original binder is not destroyed by the treatment to which the reground cork granules are subjected in our process. 45

In accordance with our invention, we treat the reclaimed cork particles (which contain approximately 25% of the original binder) with a partially formed synthetic resin binder which contains one or more ingredients which will prevent 50 a decomposition of formaldehyde-gelatine in the presence of water under either heat or pressure or both. Instead of using the partially formed synthetic resin binder, we may use the ingredients of such a binder. The ingredients .of such a syn- 55 When the scrap from the 20- thetic resin binder that will prevent the decomposition of the formaldehyde-gelatine are aldehydes, ketones, phenols and the like. We may use any partially formed soluble form of phenol aldehyde condensate or a partially condensed formaldehyde urea resin. It is necessary to have some active aldehyde, ketone or phenol present in the synthetic resin binder in order to prevent a partial reversion of the original binder into glue and formaldehyde.

As an example of our new cork composition, we may add to 150 pounds of ground cork, reclaimed from previously formed cork composition, 21 pounds of a binder consisting of 10 pounds of A stage phenol formaldehyde condensation product and 10 pounds of a plasticizing agent such as glycerine, di-ethylene glycol or any of the glycols.

The proportion of binder added is not dependent upon the amount of original binder left in the reground cork composition. Accordingly, it is not necessary for us to keep scrap cork separated according to the amount of binder originally present. All the cork composition scrapped, after gaskets or crowns or any similar articles are cut therefrom, is run through a suitable mill to regrind it into particles of the desired size. The cork composition formed from the reground scrap has very little shrinkage and may be used for gaskets, crowns or for any other uses for which ordinary cork composition is fitted.

Some soft drinks, such as chocolate drinks, must be processed for about thirty minutes at a temperature of approximately 245 F. after they have been bottled, in order that the contents may be kept for a reasonable length of time without spoiling. Ordinary crowns cannot withstand this processing treatment because of the disintegration of the binder. Heretofore, in making crowns for such drinks, it has been necessary to resort to special binders Which added considerably to the expense of the completed cap. Our reclaimed cork can stand such processing operations without any indication of disintegration of the binder.

Although we have described our cork composition as made of reground cork composition in which the original binder was formed of a protein, a softening agent and a tanning agent, it is possible to use reground cork composition in which the original binder was a synthetic resin for this purpose.

Although we have described our invention in some detail, it is to be understood that various details may be modified without departing from the spirit or scope of our invention and we do not desire to be restricted to the specific details described except as limited by the appended claims.

We claim:

1. In the method of reclaiming cork composition containing a tanned protein binder, the steps consisting in comminuting cork composition containing a tanned protein binder, treating the comminuted mass with a partially condensed phenol-aldehyde resin which inhibits decomposition of the tanned protein binder during the forming and baking operations, and forming and baking the treated comminuted mass under pressure.

2. A composition of matter comprising granules 5 containing particles of cork and particles of a tanned protein binder, and a partially condensed phenol-aldehyde resin which binds the granules into a homogeneous mass and inhibits decomposition of the tanned protein binder.

3. In the method of reclaiming cork composition containing a tanned protein binder, the steps consisting in comminuting cork composition containing a tanned protein binder, treating the comminuted mass with an aldehyde and a. reaction substance therefor selected from the group consisting of urea and phenols to bind the comminuted mass and inhibit decomposition of the tanned protein binder during a subsequent baking step, and baking the treated comminuted mass.

4. In the method of reclaiming cork composition containing a tanned protein binder, the steps consisting in comminuting cork composition containing a tanned protein binder, treating the comminuted mass with an aldehyde and a reaction substance therefor including a, phenol to bind the comminuted mass and inhibit decomposition of the tanned protein binder during a subsequent baking step, and baking the treated comminuted mass.

5. In the method of reclaiming cork composition containing a tanned protein binder, the steps consisting in comminuting cork composition containing a tanned protein binder, treating the comminuted mass with an aldehyde and a reaction substance therefor including urea to bind the comminuted mass and inhibit decomposition of the tanned protein binder during a subsequent baking step, and baking the treated comminuted mass.

6. A composition of matter comprising granlues containing particles of cork and particles of a tanned protein binder, and an at least partially condensed binding material containing an aldehyde and a reaction substance therefor selected from the group consisting of urea and phenols, said binding material inhibiting decomposition of the tanned protein binder.

'7. A composition of matter comprising granules containing particles of cork and particles of a tanned protein binder, and an at least partially condensed binding material containing an aldehyde and a reaction substance therefor including a phenol, said binding material inhibiting decomposition of the tanned protein binder.

8. A composition of matter comprising granules containing particles of cork and particles of a tanned protein binder, and an at least partially condensed binding material containing an aldehyde and a reaction substance therefor including urea, said binding material inhibiting decomposition of the tanned protein binder.

HERBERT PASCHKE. CLARENCE C. VOGT. 

